1. Field of the Invention
This invention relates generally to methods for making insulated wires, and more particularly to methods for making insulated superconductor wires.
2. Description of the Related Art
The phenomenon of superconductivity was discovered by K. H. Onnes in 1911 when he demonstrated that the electrical resistance of mercury drops to zero when it is cooled to approximately 4.degree. Kelvin (K) above absolute zero temperature. For many years the phenomenon remained a scientific curiosity, with few practical uses.
Theoretically, superconductivity has many potential uses. For example, superconducting power lines save a great deal of energy which is otherwise dissipated during transmission. Superconducting magnets, generators, and motors are small and extremely powerful. Superconducting devices known as Josephson junctions are extremely fast electronic switches having very low power consumption. In fact, the potential uses for superconducting materials are so many and varied, that an attempt make a comprehensive list of possible applications is almost an exercise in futility.
Despite the potential benefits of superconducting devices and structures, in the past they were seldom found outside of research laboratories because it was too expensive to cool most materials to their superconducting transition temperature T.sub.c. This was due to the fact that, prior to early 1987, all known superconductor materials had a transition temperature within a few dozen degrees Kelvin of absolute zero, requiring the use of expensive liquid helium cooling systems.
On Mar. 2, 1987, M. K. Wu et al. published a paper entitled "Superconductivity at 93 K in a New Mixed-Phase Y--Ba--Cu--O Compound System at Ambient Pressure" in Physical Review Letters, Volume 58, Number 9. This announcement caused considerable excitement in the scientific and business communities because, for the first time, a superconductor material had been discovered which could use liquid nitrogen as a coolant. Since liquid nitrogen cooling systems are at least an order of magnitude less expensive than liquid helium cooling systems, many applications for superconductors suddenly became practical after Wu et al.'s discovery.
The superconductor material YBaCuO has a ceramic-type structure which brittle and hard to work with. For this reason, the related art fails to teach a method for making economical, durable superconductor wire from YBaCuO or related substances.